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Pregnancy is basically a physiological procedure, which involves a great figure of physiological alterations, impacting virtually all the organ systems in the organic structure. By the terminal of the first 12 to 14 hebdomads, most of these alterations would hold reached an appreciable magnitude. Indeed, it is believed that most of these alterations are initiated in the luteal stage of every ovulatory catamenial rhythm ; the formation of principal luteum of gestation merely accentuates the state of affairs ( Chapman et Al, .

1997 ) . Therefore, the catamenial rhythm maps, non merely to bring forth fresh eggs each month, but besides acts proactively to fix the organic structure for gestation.The alterations in ventilatory map during gestation may be unrelated to the obvious anatomical alterations, which occur because of upward supplanting by the gravid womb.

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The sub-costal angle additions increasingly from 68 grades in early gestation to 103 grades in late gestation and returns to normal within a few hebdomads of bringing ( Thomas et al. , 1938 ) .Furthermore, it has been noted that the cross diameter of the chest wall additions by about 2cm while the stop is raised by about 4cm ( Thomas et al. , 1938, McGinty 1938 ) . However, the entire lung capacity decreases merely somewhat because of compensatory addition in the transverse and antero-posterior diameters of the thorax, every bit good as flaring of the ribs ( Broughton-Pipkin 2007 ) . In the respiratory piece of land, hormonal alterations stimulate the mucosal vasculature taking to capillary engorgement and puffiness of the liner of the olfactory organ, oropharynx, voice box, and windpipe.

Airway opposition is reduced, doing increased airing and decreased partial force per unit area of CO2. This may likely be due to the progesterone-mediated relaxation of ligaments and relaxation of the bronchial muscular structure. ( Lyons and Anthonio 1959 ) .Despite the upward supplanting, the stop moves with greater jaunts during take a breathing in the pregnant than in the non-pregnant province.

In fact, external respiration is more diaphragmatic than thoracic during gestation ; an advantage during supine placement and high regional encirclement ( Lyons and Anthonio 1959 ) . From the center of the 2nd trimester, expiratory modesty volume, residuary volume and functional residuary capacity are increasingly decreased, by about 20 % at term ( Berry and McMurray 1989, Sroczynski 2002, McAuliffe et al. , 2004 ) . Lung conformity is comparatively unaffected, but chest wall conformity is reduced, particularly in the lithotomy place.

A progressive addition in infinitesimal airing starts shortly after construct and extremums at 50 % above normal degrees around the 2nd trimester. This addition is effected by a 40 % rise in tidal volume and a 15 % rise in respiratory rate ( Lyons and Anthonio 1959, Liberatore et al. , 1984 ) . Since dead infinite remains unchanged, alveolar airing is approximately 70 % higher at the terminal of gestation. The increased airing decreases arterial and alveolar C dioxide tensenesss. An mean paCO2 of 32 mmHg ( 4.

3 kPa ) and arterial O tenseness of 105 mmHg ( 13.7 kPa ) persist during most of gestation ( Lyons and Anthonio 1959 ) .These alterations have far making clinical deductions, as anterior cognition will help greatly in the direction of pregnant adult females with respiratory upsets. Furthermore, normal pregnant adult females besides undergo important alterations in ventilatory map during spinal anesthesia ( Lyons and Anthonio 1959, Kelly et al. , 1996 ) .This survey, therefore, purposes at by and large and specifically measuring some ventilatory map alterations as they affect normal pregnant adult females in our environment. Respiratory alterations in gestation are of clinical importance to the anesthesiologist, during disposal of anesthesia to pregnant adult females particularly during childbearing and specifically during cesarean subdivision.

This survey will help in acquiring baseline values in all the trimesters of gestation, to enable accurate reading of spirometric values in the direction of clogging or restrictive lung diseases during gestation.


3.1 Study Area

The survey is a descriptive cross sectional survey carried out at the antenatal and booking clinics of the University of Nigeria Teaching Hospital ( UNTH ) , Ituku-Ozalla and Kenechukwu specialist infirmary Enugu and Chukwuasokam maternity infirmary in Emene between April and July 2010.

3.2 Ethical Clearance

Ethical clearance was obtained from the ethical commission of the UNTH, Enugu.


3 Sampling Size and Sampling Technique ;

To cipher the minimal sample size for comparing the agencies of FVC, FEV1, PEFR, and, FVC/FEV1 and their assorted per centum predicted values among the groups, the undermentioned expression was used ( Campbell and Machin 1996 ) :n = 2 ( Z? + Z ) 2 ?? 2?2where n = lower limit sample size in each groupZ? = % point of the normal distribution matching to the one – sided significance degree ( e.g. if significance degree is 5 % , so Z? = 1.65 )Z = one sided per centum point of the normal distribution ; matching to the power. If the power is 80 % so Z = 0.84.? = Population Standard divergence? = m2 – M1 = expected difference in agenciesFrom, old surveies the expected mean differences ranges from 5 % to 10 % .

For FVC, FEV1, PEFR, and ERV ; the mean population standard divergence is about ± 0.76 and the mean average difference is about 0.56Therefore n = 2 ( 1.65 + 0.84 ) 2 x 0.

762( 0.56 ) 2= 12.4002 ten 0.58 = 230.31For the per centum predicted values, the mean population standard divergence is about ± 15 while the mean average difference is about 10.n = 2 ( 1.

65 + 0.84 ) 2 x 152( 10 ) 2= 12.4002 ten 225 = 28100Therefore, the minimum sample size for this survey is about 28 for each group doing 112. However, we recruited 200 pregnant adult females and 100 non-pregnant by systematic random trying. This was to take attention of those who will non finish the strict procedures involved in standard spirometry.


4 Inclusion Criteria

All confirmed pregnant adult females who do non hold any of the exclusion standards.Willingness to take part.Ability to show sufficient proficiency in transporting out the trials needed to measure ventilatory map.


Exclusion Standards

Patients with the followers will be excluded:Pre bing cardio-respiratory diseases like asthma, Chronic ObstructiveAirway Disease ( COPD ) , Congestive Cardiac Failure ( CCF ) .Presence of spinal malformations ( scoliosis, kyphoscoliosis )Upper and lower respiratory tract infections.Medicines that alter lung map ( e.g. bronchodilators and constrictors ) .

Acute malaria in gestation.Preeclampsia.Diabetess in gestation.Other gestation complications ( threatened abortion, prenatal bleeding etc ) .HIV positive patients.Smokers.

Subjects who had worked or who work in dust-covered environments like coal excavation or street sweepers.Others include feverish conditions, multiple gestation, chronic nephritic disease, reaping hook cell anemia.For optimum and quotable consequences to be obtained, the followers was avoided ;Devouring intoxicant within four hour of proving.Vigorous exercising within 30 proceedingss of proving.Wearing apparels that well restrict chest and abdominal motionEating big repast within two hours of proving.Chest or abdominal hurting of any aetiology.Pain in the oral cavity or face that will be worsened by mouthpiece, dementedness or confusional province and emphasis incontinency ( Miller et al, .

2004 ) .These were clearly explained to these topics during reding in the engagement clinic. Those who met the standards were tested instantly while the remainders were followed up later to their several prenatal clinics.

3.6 Control Population

They were recruited from normal non-pregnant female staff of the UNTH Enugu, who met the inclusion standards for the pregnant topics. These topics were matched for age, and tallness. Pregnancy was be ruled out by executing the trial on the seventh twenty-four hours of the last normal catamenial period and performing gestation trial utilizing early forenoon piss.

3.7 Recruitment of Study Subjects

Subjects were recruited by systematic random sampling of all the adult females at assorted trimesters that were resident in Enugu province and go toing the prenatal clinic.

The method of enlisting was besides same for the non-pregnant control topics. One out of every two patients go toing the ANC was recruited by simple random trying utilizing a lucky dip of yes or no. Verbal informed consent was besides obtained from the patients. After obtaining ethical clearance and informed consent, approximately 300 patients who meet the above standards were recruited.

3.8 Methods

A pre-tested questionnaire patterned after the 1976 British MRC questionnaire on respiratory symptoms, as modified by Pistelli et Al. ( 2001 ) was used.

Some house officers were trained on the disposal of the questionnaire and they obtained obtain the information straight from the topics. These include, general information, familial diseases, general diseases, respiratory diseases, respiratory symptoms, allergic symptoms, active smoke, inactive smoke, occupational history, environmental conditions, societal and economic conditions, diet, physical activity, day-to-day activity form, usage of respiratory medical specialties, usage of wellness services, wellness position and quality.English linguistic communication combined with common where necessary was used by the research worker in administrating the questionnaire. The undermentioned history were obtained from the topics ; personal history, history of present gestation, past obstetric history, past medical history, household and societal history and reappraisal of systems.

The gestational age was assessed from the last normal catamenial period. Merely those who were certainly of their last catamenial period were included. Trimester was defined as first trimester ( & A ; lt ; 14 hebdomads ) , 2nd ( 14 hebdomads – 27 hebdomads ) and 3rd ( & A ; gt ; 27weeks ) . Clinical and obstetric scrutinies were performed. Axillary temperature was taken to except febrility and temperature of less than 37.5oc was considered as normal.The undermentioned anthropometric measurings were performed ;Weight was measured to the nearest 0.5 kg utilizing a standard weighing graduated table ( STADIOMETER, SECA, MODEL 220, GERMANY ) .

The tallness was measured in metres, without places, with the pess together, standing every bit tall as possible with the eyes degree and looking consecutive in front. Measurement was done to the nearest centimetre utilizing a standard measurement stick. ( STADIOMETER, SECA, MODEL 220, GERMANY ) .All the topics and controls were subjected to the same instrument and method of measuring.Body mass index was calculated by spliting the weight in Kg with the square of the tallness in metres and expressed as Kg/m2.

The mid-upper arm perimeter ( MUAC ) , which is the perimeter of the upper arm at that same center, was measured in centimeters with a non-stretchable tape step. The waist perimeter was measured by turn uping the iliac crest and thenceforth using a tape above it inquiring the participant to wrap it round them. The tape was checked to do certain it was horizontal across the dorsum and forepart of the topics. The hip perimeter was measured by positioning the measurement tape around the maximal perimeter of the natess at the degree of the inguen ( NHANES III ) .


9 Equipment and Procedure

The ambient temperature was measured on each twenty-four hours. The respiratory rate was besides measured. A standard Spirometer ( Micro lab ML3500 MK8, Cardinal Health Germany 234 GMBH ) with disposable oral cavity piece was used throughout the survey to find some forced ventilatory maps ( FEV1, FVC, FVC/FEV1, and PEFR ) .This involve general and where necessary single presentation of how best to blow the spirometer.

Subjects were relaxed, and dentures removed, tight suiting fabrics loosened. Ambient temperature, barometric force per unit area and clip of twenty-four hours and place of measuring were recorded. The clip of twenty-four hours was within 2 hour of old trial times.Although testing may be performed in either the posing or standing place ( Townsend 1984, ATS 1979 ) , the sitting place was used for safety grounds in order to avoid falling due to syncope associated with gestation. The chair had weaponries and without wheels. The age, weight, tallness and cultural beginning of the topics are keyed into the equipment and so customized to mensurate either the forced or the relaxed spirometric indices. Capable were instructed to sit unsloped in a consecutive backed chair, with belt loosened, breath usually for a minute, so take a deep breath every bit much as possible and use the lip around the mouth piece of the spirometer steadfastly. She so breathes out as rapidly and every bit forcibly as possible into the spirometer.

Checks were made to guarantee there were no escapes of air from the mouthpiece. Procedure was repeated if there was any escape. The equipment automatically selects the best out of three manoeuvres when the American Thoracic Society/European Respiratory Society ( ATS/ERS ) guidelines must hold been met ( three good blows with values within 5 % or 0.

15 liter ( 150 milliliter ) . The spirometer has an built-in mechanism that automatically rejects consequences associated with hapless technique.Prevention of infection transmittal was achieved through proper manus lavation and usage of barrier devices, such as suited baseball mitts. Handss were washed instantly after direct handling of mouthpieces, tubing, take a breathing valves or interior spirometer surfaces. Baseball gloves were worn when managing potentially contaminated equipment if the practician has any unfastened cuts or sores on his/her custodies. Handss were ever washed between patients. To avoid cross-contamination, take a breathing tubings, valves and manifolds were disinfected or sterilized on a regular basis. Any other equipment that comes into direct contact with mucosal surfaces were disinfected, sterilized or, if disposable, discarded after each usage.

3.10 Statistical Analysis.

Valuess were recorded per centums and intend ± criterion divergence where applicable.

Analysiss of informations were done utilizing Statistical Package for Social Sciences ( SPSS ) version 11, graph tablet prism version 5.02 and chart pad prism province mate version 2.00. Normality trials were performed and comparing of mean was done by the one-way analysis of discrepancy ( ANOVA ) if informations obeyed Gaussian distribution However where informations did non obey Gaussian distribution, the kruskal Wallis trial was used. These were nevertheless followed by Tukey, s candidly important station hoc multiple comparing.

The respiratory map indices in gestation were compared with the values found in the matched controls.


Socio-Demographic Features

Out of the three hundred subjected recruited, 172 ( 40 control, 30 first trimester, 48 2nd trimester and 54 3rd trimester ) met the ERS/ATS quality control. Sociodemographic features of the topics are represented in table 1.

Forces Vital Capacity ( FVC ) and Percentage Predicted FVC

The mean values for FVC and the per centum predicted are shown in table 4. For the per centum predicted the alterations are chiefly due to differences between control versus 2nd trimester ( P=0.006 ) and command versus 3rd trimester ( P & A ; lt ; 0.

0001 ) .

Forced Expiratory Volume in One Second ( FEV1 ) and Percentage Predicted.

The mean values for FEV1 and the per centum predicted are shown in table 5. For the per centum predicted the alterations were chiefly due to differences between control versus 2nd trimester ( P=0.033 ) and command versus 3rd trimester ( P & A ; lt ; 0.0001 ) .

Peak Expiratory Flow Rate ( PEFR litres /second ) and Percentage Predicted

The mean values for PEFR and the per centum predicted are shown in table 6.

The alterations in the per centum predicted was chiefly due to differences between control versus 3rd trimester ( P=0.021 ) .

4.7 Ratio of FEV1/FVC ( % ) and the Percentage Predicted

The mean values for FEV1/FVC and the per centum predicted are shown in table 7. For the per centum predicted the alterations were chiefly due to differences between control versus 2nd trimester ( P=0.

033 ) and command versus 3rd trimester ( P & A ; lt ; 0.0001 ) .

Figure 7: Average FEV in one second/FVC during gestation

Chapter FIVE


All the topics were within the generative age group and there were no important alterations between the age groups.

The fact that the highest para occurred in the control group represents a choice prejudice as most of those who met the choice standards for the control population had completed their households. Expectedly, the chest perimeter increased as gestation progressed. Earlier surveies had demonstrated this phenomenon ( Thomas et al. , 1938, Gibson 1966, Broughton-Pipkin 2007 ) .During gestation, insufficient or inordinate weight addition can compromise the wellness of the female parent and fetus and besides affect lung map.

All the topics had formal instruction. Indeed the bulk had secondary instruction as the least making. Again, this represents a choice prejudice, as the nonreaders that were ab initio recruited had troubles understanding the direction to be followed during spirometry. Indeed, deficiency of apprehension of the process besides led to the inability of the most of the recruited topics to run into the ERS standards on quality control.The FVC and the per centum predicted and the FEV1 and the per centum predicted were within normal scope in both the non-pregnant and pregnant topics.

However, the values decreased significantly, as gestation progressed. Although some earlier surveies did non show any important alteration in these parametric quantities during gestation ( Puranik et al.,1994, Chhbra et al.

,1988 ) , nevertheless, bulk and more recent surveies agreed with our findings ( Mokkapatti et al.,1991, Lui 1992, Neeraj et al.,2010 )This survey besides demonstrated that PEFR was normal in all the topics but decreased more significantly during gestation. Conversely, the per centum predicted values showed a important diminution. The findings in the PEFR from most surveies varied wildly depending on the equipment and the geographic location.

While some surveies agreed with our findings ( Mokkapatti et al.,1991, Puranik et Al, .1995, Neeraj et al.

,2010 ) , others did non illicit any important diminution ( Brancazio et al. , 1997, Salisu et Al, . 2007 ) .The FEV1/FVC ratio increased significantly, as gestation progressed. In a survey in northern India, this parametric quantity besides increased but none significantly ( Neeraj et al.,2010 ) .It was noted that the magnitude of lessening in FEV1 during gestation was non every bit much as the lessening in FVC. The effect of this differential alteration is the rise in the FEV1/FVC ratio.

The lessening in FVC in our survey may be due to a comparative lessening in the negativeness of the intrapleural force per unit area occasioned by an upward supplanting of the stop by the enlarging womb ( Shaikh et al 1983 ) . Decrease in FEV1, and PEFR may be due to a diminution in alveolar PCO2 ( caused by hyperventilation ) . In the respiratory piece of land, hormonal alterations stimulate the mucosal vasculature taking to the decrease in air passage opposition. This leads to increased airing and decreased partial force per unit area of CO2. This may likely be due to the progesterone-mediated relaxation of ligaments and relaxation of the bronchial musculuss ( Lyons and Anthonio 1959 ) . Furthermore, the lessening in PEFR could be due to lesser force of contraction of chief expiratory musculuss like the anterior abdominal wall musculuss and internal intercostals musculuss ( Phatak et al 2003 ) .

In add-on, it has been demonstrated that decreased haemoglobin degree in gestation causes musculus failing and this significantly affects ventilatory musculuss. ( Puranik et al.,1995, Neerag et al. , 2009 ) . Majority of pregnant adult females in Nigeria are anemic and this may negatively impact the strength of contraction of the respiratory musculuss ( Ogunbode 1984, Nwagha et al.

,2009 ) .The decreased value for FVC, lower FEV1 with higher FEV1/FVC is an indicant that some grade of ventilatory limitation occur during gestation in our environment ( Pellegrino et al. , 2005 ) .

This phenomenon is physiological procedure that consequences from the decrease in lung volume occasioned by the turning womb. Indeed, a farther lessening in lung volume occurs during the early stage of each uterine contraction, ensuing from redistribution of blood from the womb to the cardinal venous pool. It is hence pertinent that, this should be taken into awareness during the diagnosing and intervention of pregnant adult females with respiratory upsets.This survey forms a baseline for the finding of alterations in some ventilatory map parametric quantities during gestation in Enugu ; South East Nigeria. The reduced FVC, PEFR, FEV1 and increased FEV1/FVC ratio is a strong indicant that gestation causes physiological limitation in the lungs.

With the combination of increased O ingestion and the reduced expiratory modesty volume due to the reduced functional residuary capacity, rapid autumn in arterial O tenseness despite careful maternal placement and pre oxygenation may happen during labor and spinal anesthesia. Even with short periods of apnea, either from obstructor of the air passage or inspiration of a hypoxic mixture of gases, the gravida has small defense mechanism against the development of hypoxia. Furthermore, the increased minute airing, combined with reduced functional residuary capacity hastens inhalatory initiation or alterations in the deepness of anesthesia when take a breathing spontaneously. The baseline values that we established are hence critical and priceless while executing these processs in normal pregnant adult females, but more particularly in adult females with compromised cardiorespiratory maps.

Table 1: Some Demographic Characteristics of the Subjects



1st trimester

2nd trimester

3rd trimester


Age ( old ages )30.75 ±5.4530.07 ± 4.

4131.50 ± 3.7629.44±5.080.165nsParity2.95 ±1.

481.83 ±1.642.25 ±2.

151.67 ±1.670.005*Chest C ( centimeter )88.87 ±4.6790.57±7.

0592.25 ±6.4497.66 ±9.

650.000*Height ( M )1.65 ±0.

061.65 ±0.051.66 ±0.061.

66 ±0.070.505nsWeight ( Kg )71.07± 9.4274.59 ±9.

8775.75 ±9.8178.61±13.620.014*BMI ( Kg/m2 )27.29 ± 2.

8227.24 ±4.1828.62 ±3.6428.83 ±3.

220.058nsMAC ( centimeter )28.55 ±2.5429.30 ±2.3329.56 ±3.

0530.50 ±4.520.

048*Hip C ( centimeter )98.85 ±8.17100.57±8.21105.

50±5.91107.56±8.570.000*Waist C ( centimeter )87.

42 ±9.5794.67 ±12.0198.56 ±8.

3499.17 ±9.250.000*C = Circumference, M= Meter. Kg = Kilogram, Cm=Centimeter,BMI= Body Mass Index, MAC= Mid Arm Circumference.Ns=non-significant ( P & A ; gt ; 0.

05 ) , * P & A ; lt ; 0.05 ) .

Table 4: Mean and Standard Deviation ( SD ) Forced Vital Capacity FVC ( litres ) and Percentage Predicted ( % ) .


FVC ( litres )

Percentage Predicted ( % )

P value

Control402.93± 0.73a100.

70±31.11e( P & A ; lt ; 0.0001 ) .1st trimester302.93 ±0.33b92.10± 1.

70f2nd trimester482.56 ±0.41c85.61± 13.20g3rd trimester542.

55 ± 0.51d82.30± 19.

01hPost-hoc multiple comparing ; a versus degree Celsius ( P=0.11 ) , a versus vitamin D ( P=0.006 ) , b versus degree Celsius ( P=0.026 ) , e versus g ( P=0.006 ) , and e versus H ( P & A ; lt ; 0.0001 ) .

Table 5: Mean and Standard Deviation ( SD ) of Forced Expiratory Volume in One Second ( FEV1, litres /s ) and Percentage Predicted


FEV1 ( l/s )

Percentage Predicted FEV1 ( % )

P value


55±0.62a102.02± 30.70e( P & A ; lt ; 0.0001 ) .

1st trimester402.47±0.24b93.40± 7.79f2nd trimester482.32±0.

36c89.44± 13.58g3rd trimester542.24±0.45d82.89±18.

32hPost hoc multiple comparing ; a versus vitamin D ( P = 0.013 ) , e versus g ( P=0.033 ) , e versus H ( P & A ; lt ; 0.0001 ) .

Table 6: Mean and Standard Deviation ( SD ) Peak Expiratory Flow Rate ( PEFR ) Liters and Percentage Predicted


PEFR ( l/s )

Percentage Predicted PEFR ( % )

P value

Control405.38±1.44a93.4 ± 32.16ea vs. B vs. degree Celsius vs.

vitamin D ( P=0.883 )vitamin E vs. degree Fahrenheit vs. g vs.

H ( P=0.014 )1st trimester305.24± 0.92b87.60 ± 5.98f2nd trimester485.21± 1.08c83.19 ± 15.46g3rd trimester545.18± 1.42d79.39 ± 20.90hPost hoc multiple comparing vitamin E versus H ( P= 0.021 )

Table 7: Mean and Standard Deviation ( SD ) of FEV1/FVC ( % ) and Percentage Predicted


FEV1/FVC ( % )

Percentage Predicted

P value

Control4087.56± 2.87a107.37 ± 3.88e( P & A ; lt ; 0.0001 ) .1st trimester3087.57± 1.38b102.97 ± 1.24f2nd trimester4890.69± 4.37c109.56 ± 5.33g3rd trimester5491.20± 4.21d105.77 ± 5.82hA versus vitamin D ( P=0.013 ) , e versus g and H ( p=0.033 )